Current transformer



D. J. ANGUS.

CURRENT TRANSFORMER. APPLICATION FILED JUNE 28. 1920.

1,415,505, v Patentd my 9,1922.

/ Fig.3.

Don aid .Ifirzgus,

GHotucg UNITED STATES DONALD J'. ANGUS, 0F INDIANAPOLIS, INDIANA.

CURRENT TRANSFORMER.

Application filed June 28, 1920. Serial No. 392,182.

To all whom it may concern:

Be it known that I, DoNALnJ. ANoUs, a citizen of the United States, residing at Indianapolis, in the county of Marion and State of Indiana, have invented a new and useful Current Transformer, of which the following is a specification. i

It is the object of my invention to provide a current transformer in which there is a wide range of transformation, sothat the same current may be supplied to the instrument for a widely varying range of current in the main circuit, as conditions require; and to use as the primary of such transformer either primary windings permanently wound thereon and connected in various combinations, or one or more loop-s of the main conductor passed through the core of the transformer, as conditions require.

With the transformer shown, it is possible to get the same secondary current from the transformer for primary currents which vary from a minimum to a maximum thirty two times the minimum.

The accompanying drawing illustrates my invention: Fig. 1 is a horizontal section through a. transformer embodying my invention, with the connections shown diagrammatically and the four primary windngs connected in series; Fi 2 is a vertical section on the line 22 of ig. 1; and Figs. 3 and 4: are diagrammatic views showing the connections with the primary windings in series-parallel and-in parallel respectively.

The transformer has a laminated crossmagnetic-circuit core 10, conveniently rectangular, with an opening through it to form two opposite legs the ends of which are magnetically cross-connected, on which two opposite legs the permanent windings are mounted. These permanent windings pass through the opening in the core, but

Where they pass through such opening they,

are together of materially smaller cross section than the opening is itself, so that the windings on opposite legs of the core are spaced apart and does not fill such opening, but instead leave a clear passage, oblong in cross section, through the opening between the windings. There are two secondary windings 1'1 and 12, mounted on these two legs and connected in series and to a pair of terminals 13 towhich the ammeter or other in- Specification of Letters Patent. I

Patented Mayo, 1922.

strument is connected; and four primary windings 15, 16, 17 and 18, shown as outside of the secondary windings, though of course not necessarily so, two primary windings be ing located on each winding-carrying leg. Each primary winding is shown as having eight turns, which is the number I prefer to use; and the secondary winding may have any desired number of turns, say one hundred and sixty for example, half on each leg. The core 10 with its primary and secondary windings is mounted in a suitable casing 19, which has an open center providing an oblong opening 20 through the core 10 and between the windings on the winding-carrying legs thereof. The casing 19 is preferably discontinuous where it extends through the core, or is interrupted transversely to the opening'through the core, to avoid eddy currents. The oblong opening 20 permits the passing through the core of from one to four loops 21 of the main conductor of the circuit in which the current is to be measured.

The terminals of the primary windings 15, I

16, 17, and 18 are connected to binding posts 22 and 23, 24 and 25, 26 and 27, and 28 and 29, respectively. These binding posts, though carried by the casing 19 as indicated in Flg. 2, are shown separately in F 1g. 1 to avoid confusion in the showing of the electric connections. The binding posts 22 and 29 may be connected into the main circuitof which. the measurement is to be taken. The binding posts are arranged in two rows, as shown in Fig. 1, with the even-numbered binding posts in one row and the odd-numbered binding posts in the other, and the posts in the second row are staggered, so that each binding post is equally'distant from the two adjacentposts in its own row and the two nearest posts in the other row. A plurality of cross connectors 32 are provided, six of these sometimes being necessary. Each cross connector 32 is preferably provided with a closed longitudinal slot 33 near one end for co-operating with one binding post and with an open longitudinal slot 34 at the other end, whereby it may be made to cooperate with any of the adjacent binding ed in series, as illustrated in Fig. 3, or in series-parallel, as illustrated in Fig. 3, or in parallel, as illustrated in Fig. 4:.

Thus by using different connections of the primary windings 15, 16, 17, and 18, or different numbers of loops 21 through the oblong opening 20, a wide variation in the ratio of transformation of the transformer is ob tainable, to adapt the same ammeter or other measuring instrument to widely varying main currents. IVith the series connection shown in Fig. 1, the total'p-rimary Winding comprises 32 turns, which with a secondary winding-having one hundred and sixty turns makes a ratio of transformation of five to one. With the series-parallel connection shown in'Fig. 3 and obtained by shifting the connectors 32, the total primary winding comprises sixteen turns, which makes a ratio of ten to one. With the parallel connection shown in Fig. 4 and obtained by further shifting of the cross connectors 32, the

total primary winding comprises eight turns,

which makes a ratio of twenty to one. If a still higher ratio is desired, the primary windings 15, 16, 17, and 18 are disconnected, and the main conductor 21 is passed in one or more loops through the opening 20. If it is passed through such opening in four loops this makes a primary winding of four turns, with a ratio of forty to one.

two loops, thls makes a primary winding of .twoturns, with a transformation ratio of eighty to one. If the primary conductor is passed through the opening 20'but once, the effect of a single turn of primary winding is obtained, with a transformation ratio of one transformer and single metering instrument to get the effect of six different meter capacities.

I claim as my invention: 1. In a current transformer, a core having 'anopening, through it, a plurality of primary win ngs on saidcore, a secondary winding on said core, said windings being permanently fixed on said core and passing through 'such opening and together being of materially smaller cross-section where they pass through such opening than such opening is itself'so that when in place they still leave a relatively large clear passage through I the same opening permitting the temporary If the main. conductor is passed through such opening ininsertion through such opening of one or more loops of a conductor to constitute another primary winding, and means for connecting the permanently fixed primary windings in different groupings to vary the ratio of transformation of thetransformer.

2. In a current transformer, the combination of a core having an opening through it, a secondary winding and four permanent primary windings on said core and. all passing through said opening in the core and together being of materially smaller crosssection where they pass through such opening than such opening is itself so that they leave a relatively large clear passage through such opening through which one or more loops of a conductor may be passed temporarily to constitute another primary winding, and means for connecting said four primary windings in series or in series parallel or in parallel as desired.

3. In a current transformer, the combination of a core having an opening through it, a secondary Winding and four permanent primary windings on said core and all passing through said opening in the core and together being of materially smaller cross-section where they pass through such openlng than such opening is itself so that they leave a relatively large clear passage through such opening through which one or more loops of a conductor may be passed temporarily to constitute another primary winding, eight binding posts to which the terminals of said primary windings are respectively connected, and cross-connectors for interconnecting said binding posts in various ways to produce connections of the primary windings in series or in series-parallel or in parallel as desired.

1. In a current transformer, a core having an openingv through it so that it forms two opposite legs having their ends cross-connected magnetically, a secondary wlndlng and a plurality of permanent primary windings on said core, said windings passing through such opening and together being of materially smaller. cross-section where they pass through it than the opening 1s itself and being arranged on opposite legs of said core to leave a relatively wide oblong passage through the opening between the 'windings on the two opposite legs so that a conductor may be passed temporarily through said oblong passage in one or more loops to constitute another primary winding, and means for connecting the permanent pIlmary windings wound on said core in a plurality of groupings.

5. In a current transformer, a corehaving an opening through it, primary and secondary windings on said core and passing through such opening and together being of materially smaller cross-section where they pass through such opening than such they pass through such of materially opening is itself so that when in place they still leave a clear passage through the same opening, the primary windings being in sections, means for connecting the sections of the primary windings in a plurality of groupings, and a casing in which said,core and its windings are mounted, said core being provided with an opening which extends through it and communicates with such passage through the core to permit the temporary insertion of a conductor therethrough to provide another primary winding.

6.' In a current transformer, a core having an opening through it, primary and second ary windings on said core and passing through such opening and together being of, materially smaller cross-section where they pass through such opening than such opening is itself so that when in place they still leave a clear passage throughthe same opening, and a casing in which said core and its windings are mounted', 'said core being provided with an opening which extends through it and communicates with such passage through the core to permit the temporary insertion of a conductor therethrough to provide another primary winding, said opening through the casing and said passage through the core being oblong so that a plurality of loops of a main conductor may be passed therethrough in a row.

7. In a current transformer, a core having an opening through it, primary and secondary windings on said core and passing through such opening and together being of materially smaller cross-section where opening than such opening is itself so that when in place they still leave a clear passage through the same opening, and a casing in which said core and its windings are mounted, said core being provided with an opening which extends through it and communicates with such passage through the core to permit the tempor'ary insertion of a conductor therethrough to provide another primary winding, said casing being interrupted transversely through said passage-to avoid eddy currents.

8. In a current transformer, a core having an opening through it, primary. and secondary windings on said core and passing through such opening and together being smaller cross-section where they pass through such opening than such opening is itself so that when in place they still leave a clear passage through the same opening, and acasing in which saidcore and its windings are mounted, said core being provided with an opening which extends through it and communicates with such passage through the core to permit the temporary insertion of a conductor therethrough to provide another'p'rimary windmg.

9. p In a current transformer, the combination of a core having an opening through it, permanent primary and secondary windings on said core and passing through such opening and together being of. materially smaller cross-section where they pass through such opening than such opening is itself so that when in place they still leave a relatively large clear passage through the same opening permitting the temporary in sertion therethrough of one or more loops of a conductor to constitute another primary winding.

10. In a current transformer, the combination of a core having an opening through it, permanent primary and secondary windings on said core and passing through such opening and together being of materially-smaller cross-section where they pass through such opening than such opening is itself so that when in place they still leave a relatively large clear passage through the same opening permitting the temporary insertion therethrough of one or more loops of a conductor to constitute another primary winding, and means for varying the effective number of turns of the first primary winding.

1]. In a current transformer, --the combination of a core having an opening through it, permanent primary and secondary windings on said core and passing through such opening and together being of materially smaller cross-section where they, i

pass through such opening than such opening is itself so that when in place they st1ll leave a through. the temporary insertion therethrough of one or more loops of a conductor to constltute another primary winding, and means for varying the ratio of transformation between the first primary and secondary windlngs.

12. In a current transformer, the combination of a core having an opening through it, permanent primary and secondary windings on said core and passm through such opening and together belng o materially smaller cross-section where they pass through such opening than such opening is itself so that when in place they still leave a clear passage through the same opening, and a conductor which can be 1nserted temporarily through such passage 1n one or more loops as desired to constltute another primary winding. c

13. In a current transformer, a core having an opening through it, primary and secondary windings on said core and passing through such opening and together being of materially smaller cross-section where they pass through such opening than such open in place they still windings are mounted,-said core being prorelatively large clear passage same opening permitting the" ing &

in one or more loops to provide another primary winding.

In witness whereof, I have hereunto set my hand at Indianapolis, Indiana, this 24th day of June, A. D. one thousand nine hundred and twenty.

DONALD c J. ANGUS. 

